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Author | Topic: Where is the evidence for evolution? | |||||||||||||||||||||||||||
DanskerMan Inactive Member |
quote:Would you mind explaining the what's and how's of gene action/duplication? ThanksS
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Peter Member (Idle past 1506 days) Posts: 2161 From: Cambridgeshire, UK. Joined: |
I thought you probably did ... but there are some
posters here who really need things spelling out so that they don't run off at odd tangents
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Peter Member (Idle past 1506 days) Posts: 2161 From: Cambridgeshire, UK. Joined: |
Your example does not elaborate what you view information
to be. On the contrary it obscures it. If the letter had said :: 'Please buy my daughter a cat.' and was mis-typed as: 'Please buy my daughter a bat.' I think there is a very clear difference in the informationcontent ... don't you?
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derwood Member (Idle past 1903 days) Posts: 1457 Joined: |
quote: Sure. Keep in mind that this will be brief and will not be a universal explanation. That is, there are lots of exceptions, etc. A gene product - a protein - does something. It can be used structurally, such as collagen or tubulin, or can be 'functional', as some say, like an enzyme or a hormone. There are several ways that organisms control the amount of each gene product being expressed. For instance, we do not need or want huge amounts of growth hormone being produced all the time. There are feedback mechanisms, where, for example, the gene product itself or some metabolic byproduct either enhances or slows down further production.There are ways to turn genes off permanently, such as those used during embryonic development. There are ways to turn genes off temporarily, and so on. Increasing the amount of gene product is not just like reading a sentence twice, at least not in most cases. There are interactions between proteins and other molecules, many of which are concentration dependant. Small amounts of protein X are fine, but double it and all sorts of new interactions occur. For example, I have posted here on more than one occasion (I think) a citation for a paper in which some experimentation had been done in mice on their HOX 11 gene, which is involved in development. Introducing mutations in the gene caused, as one might expect, deformities in the mouse pups. However, when the invesigators added a second, non-mutated copy of the gene, not only were the defects 'corrected', but phenotypic changes were introduced. If I recall, these included some extra vertebrae and longer limbs.In this example alone, we see a demonstration of the fallacy of the language analogy. Writing a sentence twice will not change its meaning, at best just the emphasis (as has 'explained' to me by a creationist "information hawk"). However, duplicating a gene can definitely have significant phenotypic effects. I'm sure Gitt or Spetner must have explained this in their books. ------------------"The analysis presented in this study unambiguously shows that chimpanzees are our closest relatives to the exclusion of other primates. This is an important point that cannot be discounted. Further, the functional genetic differences that are represented by nonsynonymous sites also show this relationship. The notion that the great apes form a functional and evolutionary grade is not supported by our analysis. Rather, humans and chimpanzees are a functional evolutionary clade." Page Not Found | University of Chicago
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DanskerMan Inactive Member |
Sure. Keep in mind that this will be brief and will not be a universal explanation. That is, there are lots of exceptions, etc.
Would you mind elaborating on these "exceptions"?
There are several ways that organisms control the amount of each gene product being expressed. For instance, we do not need or want huge amounts of growth hormone being produced all the time. There are feedback mechanisms, where, for example, the gene product itself or some metabolic byproduct either enhances or slows down further production.
How does evolutionary thinking explain such control mechanisms?, ie. how they evolved.
There are ways to turn genes off permanently, such as those used during embryonic development. There are ways to turn genes off temporarily, and so on. Increasing the amount of gene product is not just like reading a sentence twice, at least not in most cases. There are interactions between proteins and other molecules, many of which are concentration dependant. Small amounts of protein X are fine, but double it and all sorts of new interactions occur.
In what cases is it like reading a sentence twice? Can you post a link again to this mice experiment. In a search I found that the limbs got shorter but not longer. Thanks,S
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derwood Member (Idle past 1903 days) Posts: 1457 Joined: |
Typical...
Did you understand what I did write? Or were you just looking for 'questions that the evo can't answer' to hang your hat on?
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DanskerMan Inactive Member |
Typical...
I'm not looking to hang my hat on anything. Your answer brought up some interesting new questions, and I simply was looking for answers, to try to understand the whole scheme. Curiosity begets information and knowledge.Did you understand what I did write? Or were you just looking for 'questions that the evo can't answer' to hang your hat on?Are you telling me that no one has the answers to my questions? If you know the answers, I would still like to know them. Thanks,S
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Admin Director Posts: 13038 From: EvC Forum Joined: Member Rating: 2.1 |
In many ways, a discussion is a search for common ground. I think Scott is saying that it is difficult to tell if any progress toward a shared understanding is being made if you don't provide any indication that you understand and/or accept the explanations. In other words, do you feel that you and Scott have walked down at least a little of the same road together? It wasn't possible to tell.
--------------------EvC Forum Administrator
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DanskerMan Inactive Member |
In many ways, a discussion is a search for common ground. I think Scott is saying that it is difficult to tell if any progress toward a shared understanding is being made if you don't provide any indication that you understand and/or accept the explanations. In other words, do you feel that you and Scott have walked down at least a little of the same road together? It wasn't possible to tell.
I am simply acting like a curious student who asks many questions of his professor in trying to get a grasp of the whole picture being presented. Is questioning disallowed?------------------ --EvC Forum Administrator We may never meet at common ground except at respect (I hope). I believe I show respect and courtesy to Dr. Page. I also think it is a good idea to ask as many questions as possible to verify or test a system or belief (as I'm sure evo's agree with). Thanks,S
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Admin Director Posts: 13038 From: EvC Forum Joined: Member Rating: 2.1 |
Hi Sonnikke,
Sonnikke writes: I am simply acting like a curious student who asks many questions of his professor in trying to get a grasp of the whole picture being presented. Is questioning disallowed? It might help to reread my message. It wasn't about questions. In general, inquiry is good and therefore questions are good. What my message was about was communication, in this case through some indication as to whether you understand what was said, and if so, do you agree or disagree. I had the somewhat the same reaction Scott did. Your questions seemed somewhat in the Socratic mode as if to point out problems or difficulties. There's nothing wrong with that approach, of course, but since the questions didn't seem informed by the responses they addressed it could be misinterpreted as indicating your not interested in explanations, and that's how discussion breaks down. I'm not taking sides in the discussion. You're perfectly free to agree or disagree with Scott as you like. I would simply like the discussion to move forward with a clear focus, but this is difficult at this point because Scott has no idea whether you understood his explanation, and if you did, whether you agree or disagree. Without this information he has no idea whether he should explain again from scratch perhaps using other words or examples, of if he simply needs to clarify a little, or if he should move on to the next point, or whether your questions were intended as some form of rebuttal.
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DanskerMan Inactive Member |
What my message was about was communication, in this case through some indication as to whether you understand what was said, and if so, do you agree or disagree. I had the somewhat the same reaction Scott did. Your questions seemed somewhat in the Socratic mode as if to point out problems or difficulties. There's nothing wrong with that approach, of course, but since the questions didn't seem informed by the responses they addressed it could be misinterpreted as indicating your not interested in explanations, and that's how discussion breaks down.
First, I'm very interested in explanations, and don't want the discussion to break down. I'm not taking sides in the discussion. You're perfectly free to agree or disagree with Scott as you like. I would simply like the discussion to move forward with a clear focus, but this is difficult at this point because Scott has no idea whether you understood his explanation, and if you did, whether you agree or disagree. Without this information he has no idea whether he should explain again from scratch perhaps using other words or examples, of if he simply needs to clarify a little, or if he should move on to the next point, or whether your questions were intended as some form of rebuttal.Second, how do you know what Scott is thinking or feeling about this? Are you two communication behind the scenes? Third, I think more clarification is needed, and I arrived at that conclusion from Dr. Page's explanation. He raised some issues by the format of his statement. ie. by saying that there are many exceptions. I want to know what the exceptions are for instance. If Dr. Page wishes to begin from scratch that would be fine, it will no doubt spur further inquiry. Thanks,S
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Admin Director Posts: 13038 From: EvC Forum Joined: Member Rating: 2.1 |
Hi Sonnikke
No need to quote so much, my message was immediately previous. It was excessive quoting that drove the decision to remove the "reply quote" button.
Sonnikke writes: First, I'm very interested in explanations, and don't want the discussion to break down. That's good to hear, because we couldn't tell.
Second, how do you know what Scott is thinking or feeling about this? Are you two communication behind the scenes? The last time Scott and I exchanged email I think he said something like, "You @#$%&*@%, how dare you suspend me, I'm never visiting your two-bit board again." (Sorry, Scott, couldn't resist ) No, Scott and I are not communicating, I'm just reading what he wrote for everyone to see, including you, in Message 203: "Did you understand what I did write?" That's why I said Scott has no idea whether you understood his explanation, because he said so openly, not because we're secretly plotting against you. As Admin I'm neutral on the issues, but highly biased against obfuscated discussion. Only in that sense am I taking sides.
Third, I think more clarification is needed... Okay, but then you're going to have to ask better questions. As I said earlier, your questions gave no indication whether you understood what was said, in fact they were phrased skeptically as if nothing was accepted, so without knowing how much, if any, of his explanations you accepted how can Scott know where to begin?
I want to know what the exceptions are for instance. I'm repeating myself somewhat now, but Scott was explaining general principles. Since he doesn't yet know if you understood the explanation of general principles, how can he embark on an explanation of exceptions? Beyond that, I think you've misunderstood Scott's use of the word "exception." I don't believe he was talking about cases where the rules don't apply, but rather situations where there are complicating circumstances. A good analogy would be explaining what constitutes a completed pass in American football. The general principle is that a pass is completed when a receiver catches it inbounds without the ball having first touched the ground. Some complicating factors:
Get the idea? And none of these complicating factors should raise any doubts about the basic principle of what constitutes a completed pass. Whew! Could you please take another stab at responding to Scott's post so that both he and those trying to follow along know what you actually thought of his post? Thanks! --------------------EvC Forum Administrator
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DanskerMan Inactive Member |
For example, I have posted here on more than one occasion (I think) a citation for a paper in which some experimentation had been done in mice on their HOX 11 gene, which is involved in development. Introducing mutations in the gene caused, as one might expect, deformities in the mouse pups. However, when the invesigators added a second, non-mutated copy of the gene, not only were the defects 'corrected', but phenotypic changes were introduced. If I recall, these included some extra vertebrae and longer limbs.
Let me give this a shot. An allele is a copy of a gene with a slight variation in the DNA sequence. Genes code for proteins which have stuctural, functional and regulatory roles in our bodies.In this example alone, we see a demonstration of the fallacy of the language analogy. Writing a sentence twice will not change its meaning, at best just the emphasis (as has 'explained' to me by a creationist "information hawk"). However, duplicating a gene can definitely have significant phenotypic effects. You are saying that alleles can cause significant phenotypic changes in an organism, and that is why it is different than two almost identical sentences. Okay so far? However, copy errors in sentences could have significant effects depending on the message in the sentence (ie. changing "hug" to "mug"). Furthermore, according to this link http://gslc.genetics.utah.edu/...s/bodypatterns/mutation.cfm it was a "downward" change due to the mutated gene (ie. loss of function), not longer limbs as you said (also no mention of vertebrae). Also according to this: http://genetics.gsk.com/link.htm, Most diseases are related in some way to our genes. The information contained in our genes is so critical that simple changes can lead to a severe inherited disease, make us more inclined to develop a chronic disease, or make us more vulnerable to an infectious disease.
Now, you were also talking about a directed experiment and not a naturally occurring event, correct? Scientists currently believe that single gene mutations cause approximately 6,000 inherited diseases. These diseases are called single gene or monogenic diseases because a change in only one gene causes the disease.In conclusion, I think that the language analogy seems still relevant (as apparantly did Percy), and it also appears that mutations causing alleles are either harmful or neutral. Anyway, it's veeeery late, and I don't know if I'm still coherent. Any thoughts? Comments? Regards,S
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Peter Member (Idle past 1506 days) Posts: 2161 From: Cambridgeshire, UK. Joined: |
I think the point being made about the limitations of the
language analogy is valid. In a written text, the accidental repetition of a wordor even full sentence produces a redundancy. The reader may pause a moment, but the copy adds nothing to the text. If you add an extra pigment gene to a flower to enhancethe colour, you end up with white (colourless) flowers. The reason for this (in violets if I remember correctly) hasbeen put down to something called RNA interference. This is a kind of primitive 'immune' response in which the 'error' is masked out. In the case above this also prevents the original pigment gene product to be masked out. The copying of one gene produced a very marked change inthe phenotype. I guess you could add it to your analogy as a destructive grammarchecker, where any grammatical errors are deleted from the text (so both copies of the repetion are not expressed in print)
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Percy Member Posts: 22499 From: New Hampshire Joined: Member Rating: 4.9 |
I'm not participating in the discussion, so I reserve my right to moderate this thread. I'm only posting a clarification since my name was mentioned.
Sonnikke writes: In conclusion, I think that the language analogy seems still relevant (as apparantly did Percy), and it also appears that mutations causing alleles are either harmful or neutral. I love the language analogy because of its explanatory power, but no analogy is perfect, and this one is no exception, as Scott and PaulK point out. The only perfect analogy to something is the thing itself. All other things produce imperfect analogies and break down at some point. Analogies are used not because they are proof or evidence, but because they help explain by putting a difficult concept into a familiar context. A common mistake that you see made here at EvC Forum is for something to be explained using an analogy, and then for the analogy to be attacked, as if breaking the analogy has any effect on the concept itself. That's not to say that false analogies can't be drawn, but even when that mistake is made it only means a mistake has been made in explication and doesn't mean the underlying concept is wrong. It certainly doesn't say it is right, either, but I just thought it was important to point out that I've seen a lot of false conclusions being drawn in discussions where analogies are used. --Percy
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